Returning Errors in COM+ using Autocomplete

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Alfredo - 07 Aug 2005 17:18 GMT

Hi,

I have a question. In my COM+ methods and functions i use Autocomplete
instead of SetComplete and SetAbort, but i dont know what do i have to
return in each function, because i have to propagate the error in my
COM+ classes, in order to function Autocomplete attribute.

What do you recommend? I think it is better do try catch and throw ex?
obviously logging the exception. This is the rigth use?

Thanks,

Alfredo Barrientos

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Tomas Restrepo (MVP) - 07 Aug 2005 19:43 GMT

Alfredo,

> I have a question. In my COM+ methods and functions i use Autocomplete
> instead of SetComplete and SetAbort, but i dont know what do i have to
[quoted text clipped - 3 lines]
> What do you recommend? I think it is better do try catch and throw ex?
> obviously logging the exception. This is the rigth use?

With AutoComplete, you need to use exceptions. The COM+/EnterpriseServices
interceptors will catch the exception and automatically vote to abort the
transaction for you. If your component needs to log the exception, just use
a try/catch block, log the exception and immediately rethrow it by using an
empty "throw;" statement in the catch block.

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Alfredo - 07 Aug 2005 22:29 GMT

Thanks Tomas,

I dont understand the last sentecen, How can i rethrow and throw a new
exception, could you show me some code?

Thanks,

Alfredo Barrientos

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Tomas Restrepo (MVP) - 08 Aug 2005 02:28 GMT

Alfredo,

> I dont understand the last sentecen, How can i rethrow and throw a new
> exception, could you show me some code?

[AutoComplete]
public void DoSomething()
{
try {
// do your main logic
} catch ( Exception ex ) {
// log ex into whetever
throw;
}
}

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/

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Alfredo - 08 Aug 2005 16:11 GMT

Thank you very much Tomas. Just one little question, "Throw" is equal
to "Throw ex"?

Thanks

Alfredo Barrientos

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Tomas Restrepo (MVP) - 09 Aug 2005 00:58 GMT

Alfredo,

> Thank you very much Tomas. Just one little question, "Throw" is equal
> to "Throw ex"?

Not at all! "throw;" just lets the current exception go on, as if it hadn't
been handled. "Throw ex;", on the other hand, throws the same exception
object as if it was a new exception altogether, and thus overwrites
important information such as the original stack trace.

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/

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Alfredo - 11 Aug 2005 17:56 GMT

Hi Tomas, thanks for answering.

I have other question, in all examples i have never seen the use of
finally in try catch instruction using autocomplete attribute in COM+
application?

Is there any trouble if i use try catch and finally with autocomplete
attribute?

Thanks,

Alfredo Barrientos

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Tomas Restrepo (MVP) - 12 Aug 2005 01:00 GMT

Alfredo,

> Hi Tomas, thanks for answering.
>
> I have other question, in all examples i have never seen the use of
> finally in try catch instruction using autocomplete attribute in COM+
> application?

The one I posted does.

> Is there any trouble if i use try catch and finally with autocomplete
> attribute?

Not as long as you still let a transaction flow out of the method on an
error (either the original one or a new exception), to ensure the
transaction gets marked for abortion. Otherwise, you'll soon meet a
wonderful set of errors with messages like "Transaction wanted to commit but
transaction aborted" and such....

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/

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Alfredo - 16 Aug 2005 17:33 GMT

Hi Tomas,

Thanks for everything! I have additional question, have you worked with
COM+ in Windows 2003 with no ApplicationAccessControl(True), and
calling it from ASP.Net Page? i am getting an error "Access Denied". My
ASP.Net is running in an application with anonymous access.

Thanks,

Alfredo Barrientos

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Tomas Restrepo (MVP) - 17 Aug 2005 00:42 GMT

Alfredo,

> Thanks for everything! I have additional question, have you worked with
> COM+ in Windows 2003 with no ApplicationAccessControl(True), and
> calling it from ASP.Net Page? i am getting an error "Access Denied". My
> ASP.Net is running in an application with anonymous access.

On .NET 1.1, if you don't use the security attributes at the assembly level
to disable security, it will be by default enabled when you register the
assembly using regsvcs.exe. If you leave it like that, you'll have to
manually go in later to the MMC console and either disable it again or
configure the necessary roles and permissions to enable access (for *any*
user or application... ASP.NET is not special in that regard).

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/

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Alfredo - 21 Aug 2005 19:06 GMT

Hi Tomas, Thanks you very much.

Do you know some guide or how to in microsoft.com which explains this
behavior?

Thanks,

Alfredo Barrientos

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Alfredo - 23 Aug 2005 19:36 GMT

Hi Thomas,

Is there any sample site like Petshop, Duwamish, Fitch & Mather, but
using COM+ Security Attributes?

Thanks,

Alfredo Barrientos

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Todd - 22 Sep 2005 20:41 GMT

Hi Tomas,

I have an additional question on this - if in your example "log ex into
whatever" means writing to a database wouldn't the fact that an exception is
being thrown cause the logged error to be rolled back as well? How can I get
that level of control over transactions? For example

<Transaction Root Here>
Public Sub DoSomething()
CreateRecordA()
try
CreateMoreRecords()
catch
CreateExceptionRecord()
UpdateRecordA_wError()
end try
End Sub

If CreateMoreRecords() fails I want to roll back any of it's updates but let
RecordA commit and also flag it as error with the Exception record logged.

Thanks
Todd Langdon

> Alfredo,
>
[quoted text clipped - 11 lines]
> }
> }

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Tomas Restrepo (MVP) - 23 Sep 2005 00:56 GMT

Todd,

> I have an additional question on this - if in your example "log ex into
> whatever" means writing to a database wouldn't the fact that an exception
> is
> being thrown cause the logged error to be rolled back as well?

Actually, we are not logging to the database there, for that very reason :)
Actually, in our case we log the error to a flat file, or the machine's
event log, for example.

> How can I get
> that level of control over transactions? For example
[quoted text clipped - 13 lines]
> let
> RecordA commit and also flag it as error with the Exception record logged.

In that case you got to call a second ServicedComponent that spawns a new
transaction (TransactionOption.RequiresNew) or gets the component out of the
existing transaction and leaves it without one
(TransactionOption.NotSupported). If you're using Windows Server 2003, you
can also accomplish this using ServiceConfig and ServiceDomain.Enter(), as
well.

Signature

Tomas Restrepo
tomasr@mvps.org
http://www.winterdom.com/

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Returning Errors in COM+ using Autocomplete

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